Systems and methods of controlling battery deterioration by controlling battery state-of-health during power exchange

ABSTRACT

A power exchange controller adjusts a power exchange rate between a plurality of batteries and an upper authority to modify a state-of-health of each of the plurality of batteries over time. The power exchange controller is operable to receive a total power demand from an upper authority and each of the plurality of batteries connected to a charging station and adjust the power exchange between the upper authority and each of the plurality of batteries by detecting a battery state-of-health of each of the plurality of batteries, determining the target state-of-health for the plurality of batteries based on the state-of-health of each of the plurality of batteries and determining a power exchange with each of the plurality of batteries based on the total power demand and a difference between the target state-of-health and the state-of-health of each battery.

TECHNICAL FIELD

This disclosure relates in general to vehicle charging stations thatcontrol vehicle battery deterioration rate using battery state-of-healthduring power exchange between the vehicle battery and an upperauthority, such as a power grid.

BACKGROUND

The automobile industry has been developing electric vehicles and hybridelectric-internal combustion vehicles (together, referred to as“electric vehicles” or “EVs”) in part to reduce emissions of carbondioxide, thereby reducing air pollution and global warming. Thedevelopment of rechargeable secondary batteries to drive the EVs is keyto making such vehicles practicable. The lifespan of these rechargeablesecondary batteries directly affects the performance of the EV, theeconomics of the EV and the perception of quality of the EV. Therefore,developing batteries that provide optimal performance and lifespan iskey to the success of EVs.

SUMMARY

Disclosed herein are systems and methods for controlling batterydeterioration. One such system for controlling battery deteriorationcomprises a power exchange controller operable to adjust a powerexchange between a plurality of batteries and an upper authority tomodify a state-of-health of each of the plurality of batteries over timetowards a target state-of-health. The power exchange controller isoperable to receive a total power demand from an upper authority andeach of the plurality of batteries connected to a charging station andadjust the power exchange between the upper authority and each of theplurality of batteries by detecting a battery state-of-health of each ofthe plurality of batteries, determining the target state-of-health forthe plurality of batteries based on the state-of-health of each of theplurality of batteries and determining a power exchange with each of theplurality of batteries based on the total power demand and a differencebetween the target state-of-health and the state-of-health of eachbattery.

The methods disclosed herein can be performed by the systems disclosedherein. One such method for controlling battery deterioration comprisesreceiving a total power demand from an upper authority and each of theplurality of batteries connected to a charging station and adjusting thepower exchange between the upper authority and each of the plurality ofbatteries by detecting a battery state-of-health of each of theplurality of batteries, determining the target state-of-health for theplurality of batteries based on the state-of-health of each of theplurality of batteries and determining a power exchange with each of theplurality of batteries based on the total power demand and a differencebetween the target state-of-health and the state-of-health of eachbattery.

These and other aspects of the present disclosure are disclosed in thefollowing detailed description of the embodiments, the appended claimsand the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features, advantages and other uses of the present apparatuswill become more apparent by referring to the following detaileddescription and drawing in which:

FIG. 1 is an illustration showing a power exchange system implemented inan example power grid;

FIG. 2 is a block diagram showing an example of a battery deteriorationcontrol system control including coordination between a power exchangecontroller of the power exchange system;

FIG. 3A is a graph of conventional alternating current powerdistribution;

FIG. 3B is a graph of alternating current power distribution based onthe systems and methods disclosed herein;

FIG. 4 is a graph of battery state-of-health over time illustrating thechange in battery state-of-health based on the systems and methodsdisclosed herein;

FIG. 5 is a graph of battery internal temperature over time illustratingthe change in battery internal temperature during power exchange basedon the systems and methods disclosed herein; and

FIG. 6 is a flow diagram of a method of battery deterioration control asdisclosed herein.

DETAILED DESCRIPTION

EVs can be charged and discharged at EV charging stations capable ofexchanging power with a number of EVs concurrently. These EV chargingstations ultimately pull power from and supply power to the power grid.Power exchange controllers are used to coordinate this supply and returnof power from and to the grid by a group of vehicles. FIG. 1 shows apower exchange system 100 and an example of an environment in which abattery deterioration control system 100 can be implemented. In theillustrated example, the battery deterioration control system 100 isimplemented in the context of a power grid 110. Although the batterydeterioration control system 100 can be implemented in the context of apower grid of any type of configuration, a typical power grid caninclude one or more power generation facilities 111 that generate andsupply electrical power, a transmission network 112 that includeslong-distance power lines, one or more power storage facilities 113 thatreceive and store electrical power when supply exceeds demand and returnelectrical power to the grid 110 when demand exceeds supply, and adistribution network 114 that receives electrical power from thetransmission network 112 and distributes electrical power to consumerssuch as businesses and homes.

The battery deterioration control system 100 includes a power exchangecontroller 120, which may also be referred to herein as a controller.The power exchange controller 120 is in communication with a pluralityof EV charging stations 130. The charging stations 130 need not be at acommon geographical location, but rather can be at multiple locations.As an example, at least a first vehicle charging station from the groupof charging stations 130 can be at a different geographical locationthan a second vehicle charging station from the group of chargingstations 130. Although referred to as “charging stations,” it isunderstood that a vehicle battery can be charged or discharged throughcharging stations 130. Essentially, the charging stations 130 are powerexchange stations as used herein.

The power exchange controller 120 is operable to receive informationfrom the charging stations 130 and is further operable to sendinstructions to the charging stations 130. The instructions that aresent from the power exchange controller 120 to the charging stations130, when interpreted by each charging station 130, are operable toregulate operation of each charging station 130. For example, theinstructions sent from the power exchange controller 120 to the chargingstations 130 can cause one or more of the charging stations 130 toperform operations such as commencing supply of electrical power to thegrid 110, commencing a charging operation, and altering characteristicsby which power is supplied to the battery during a charging operation orconsumed from the battery during a discharging operation. The powerexchange controller 120 can be implemented in the form of a system thatincludes a processor that is operable to execute instructions that arestored on a computer readable storage device, such as RAM, ROM, a solidstate memory device, or a disk drive. The power exchange controller 120can further include a communications device for exchanging informationwith other computing devices via a communications network.

Each of the charging stations 130 is connected to the power grid 110 inany suitable manner, is operable to receive electrical power from thepower grid 110, and is also operable to supply electrical power to thepower grid 110. The charging stations 130 are further in communicationwith the power exchange controller 120 for sending information to thepower exchange controller 120 and receiving information and/orinstructions from the power exchange controller 120. As explained withrespect to the power exchange controller 120, the charging stations 130can each include a system that includes a processor that is operable toexecute instructions that are stored on a computer readable storagedevice, which controls operation of each charging station 130. Each ofthe charging stations 130 can be an on-board charging station that isdisposed within the vehicle and forms a part of the vehicle or may be anoff-board charging station to which the vehicle is connected by, forexample, a charging cable. In both cases, the charging stations 130 arein communication with the power exchange controller 120 by a wiredcommunications link or a wireless communications link, where a wirelesscommunication link is defined where no direct wired communicationconnection to the charging station 130 is required.

Each of the charging stations 130 can include a power converter that isoperable, for example, to convert alternating current electrical powerthat is received from the grid 110 to direct current electrical powerthat can be used for charging the batteries of a vehicle that isconnected to the charging station 130, as well as to convert directcurrent electrical power as received from the vehicle into alternatingcurrent electrical power that can be returned to the power grid 110. Thecharging stations 130 are each operable to regulate the process by whichpower is converted. For example, each of the charging stations 130 cancontrol the wave form of the alternating current power that is suppliedto the battery or returned to the power grid 110, such as by modifyingthe frequency and/or amplitude of the alternating current electricalpower.

FIG. 2 is a block diagram showing an example of the batterydeterioration control system. The power exchange controller 120 is usedto coordinate exchange of power between an upper authority 111 and EVbatteries connected to the upper authority 111 through the chargingstations 130. The upper authority 111 can include, but is not limitedto, the power grid 110 or a building or facility which is provided powervia the EV batteries without first being routed to the grid 110. As anon-limiting example of power coordination, the controller 120 maydemand power from an EV to decrease a peak energy consumption of anupper authority 111 such as a building if the EV battery has sufficientcapacity at a peak consumption time. As another example of coordination,the controller 120 may request power to be exchanged with a connected EVbattery to assist with frequency regulation of the power grid 110. As afurther example of coordination, the controller 120 may request power tobe exchanged from one connected EV battery to another connected EVbattery in a vehicle-to-vehicle (V2V) charging operation.

As previously explained, the power exchange controller 120 is incommunication with a group of charging stations 130. Although threecharging stations 130 are shown in the illustrated example, any numberof charging stations 130 can be included in the group of chargingstations 130. Each of the charging stations 130 is associated with arespective vehicle, such as a first vehicle having a battery A, a secondvehicle having a battery B and a third vehicle having a battery C. Thecharging stations 130 are each associated with their respective vehicleby an electrical connection, shown by the solid lines, for performingpower exchange operations, and the charging stations 130 can be on-boardor off-board, as previously explained. The charging stations 130 are allconnected to the power grid 110. Communication lines are shown as brokenlines.

The batteries of an electric vehicle have a capacity, which representsthe maximum amount of power that the battery can store at a given time.Rechargeable batteries have an original capacity when new, and thatcapacity decreases over time with repeated power exchange cycles.State-of-health is a metric that compares the current capacity of abattery to its original capacity. Each charging station 130 is operableto determine a state-of-health for the battery of the respective vehicleto which it is connected. Each charging station 130 can be operable todetermine state-of-health directly, or can be operable to receivestate-of-health information from the respective vehicle, as determinedby an on-board system of the respective vehicle.

The lifespan of an EV battery depends mainly on the battery'sstate-of-health which, in turn, depends in part on the temperature ofthe battery during a power exchange, with a battery's output decreasingas its temperature increases. The temperature of a battery depends onthe battery's size, age, internal resistance, state of charge and chargeprotocol. Temperature, state of charge and charge protocol varydepending on how the batteries are used and in what environmentalconditions they are used. Because the temperature, and thusstate-of-health, can be dependent on factors that vary from vehicle tovehicle, such as how the battery is used and the environmentalconditions in which it is used, batteries produced at the same facilityin the same time period, for example, can each experience performancedegradation at varying rates. These varying rates in degradation canhave a negative impact on the perceived value, quality and economics ofthe battery, and in turn, the EV. As temperature of the batteryincreases during a power exchange, the deterioration of the batteryincreases, i.e. the state-of-health will decrease. The batterydeterioration control system and methods herein control batterydeterioration by controlling changes in a battery's state-of-healthduring power exchanges over the lifetime of the battery to balance thedeterioration of all batteries. The systems and methods herein adjustthe power exchanged with the battery as the battery's state-of-healthchanges.

Referring to FIG. 2, conventionally, EVs connect to the power grid 110at a charging station 130 as illustrated. The power exchange controller120 will detect a state-of-charge of each battery A, B, C, detect thepower demand of the upper authority 111 and determine the power demandfor each battery to be exchanged between each battery and the upperauthority 111. The power exchange controller 120 will calculate thepower demand P_(A), P_(B), P_(C) of each of the three batteries A, B, C,by dividing the total power demand P_(T) by the number of EV batteries,being three in this example. As used herein, “power demand” refers to anabsolute power and includes both power to be charged to the batteriesand power to be drawn from the batteries depending on which is requiredat a point in time during a battery's connection. FIG. 3A illustratesthe total alternating current power demand P_(T) having a frequency andamplitude, with the amplitude being divided equally to the three EVbatteries, so that P_(A)=P_(B)=P_(C). The frequency may fluctuate tomaintain the voltage and/or the current frequency of the upper authority111, and is shown constant in FIGS. 3A and 3B by means of example only.For instance, the upper authority may select and dynamically change thecharacteristics (e.g. current, voltage, power, frequency) the totalpower demand P_(T) to maintain a power grid frequency of power grid, orreduce a peak power consumption of a building.

Assuming for the sake of example that batteries A, B, C each have anequivalent internal resistance of 0.1 ohm, but battery A has astate-of-health of 90% while batteries B, C each have a state-of-healthof 100%. If batteries A, B, C exchange equal power, i.e., equalfrequency and amplitude, batteries A, B, C will deteriorate at anequivalent rate, maintaining the difference in state-of-health betweenbattery A and batteries B, C, as illustrated by the broken lines in FIG.4. Because of the power exchanged with each battery A, B, C is equal andeach battery A, B, C has the same internal resistance, the internaltemperature during power exchange of each battery A, B, C is equivalent,as shown by the broken line in FIG. 5.

The systems and methods herein control battery deterioration using thepower exchange controller 120 that is operable to adjust a powerexchange between a plurality of EV batteries and a power grid to modifythe state-of-health of each of the plurality of EV batteries to obtainan optimal life of the plurality of batteries.

A method for controlling battery deterioration is shown in FIG. 6. Instep S10, when one or more EVs connect to one or more charging stations130, the power exchange controller 120 determines a total power demandof the system from the power demand of the upper authority 111 and fromeach of the connected batteries' state-of-charge. The total power demandcan also be based on user inputs that might alter an individualbattery's demand. For example, if a user requires a full charge at aspecific time, the power exchange controller 120 must adjust the powerdemand for that battery, and in turn, the total power demand, to providethat battery with the requisite power at the requisite time.

In step S12, the battery state-of-health of each of the connected EVbatteries is detected. The battery state-of-health can be detected, forexample, by the power exchange controller 120 from an on-board vehiclecomputer. In step S14, a target state-of-health is determined for theplurality of batteries connected to the charging stations. The targetstate-of-health is based on each state-of-health of all batteriesconnected, the target state-of-health being the same for each of theconnected batteries. The target state-of-health can be determined usinga preprogrammed equation. As non-limiting examples, the targetstate-of-health can be determined by averaging the states-of-health forthe plurality of batteries connected. The target state-of-health canalso be a predetermined value that is programmed into the system. Forexample, the target state-of-health may be set to a value independent ofthe actual state-of-health of the batteries that are connected. Thetarget state-of-health can be a predetermined sliding scale depending onthe actual states-of-health of the batteries connected.

In step S16, a power exchange for each of the connected EV batteries isdetermined based on the total power demand and a difference between abattery's respective state-of-health and the target state-of-health. Thepower exchange P_(A), P_(B), P_(C) for each of the connected batteriestogether will be equal to the total power demand P_(T). As illustratedin FIG. 3B, the total power demand P_(T) to all of the connected EVbatteries is maintained by adjusting an amplitude of the power exchangeby each of the connected batteries A, B, C. Either the amplitude ofalternating current power or direct current power can be adjusted.

The calculated power exchange for each connected battery is exchangedbetween each respective battery and the upper authority 111 in step S18.The steps are dynamically repeated for each battery while the battery isconnected to the power exchange controller 120 through the chargingstation 130. The method ends for a particular battery when that batteryis disconnected, and the method can continue for the remaining connectedbatteries.

Referring back to FIG. 4, the broken lines represent the state-of-healthof each of batteries A, B, C without the battery deterioration controlsystem, and the solid lines represent the state-of-health of each ofbatteries A, B, C as power is exchanged using the battery deteriorationcontrol system and method. It should be noted that due to the dynamicnature of the system, that actual lines may not be truly linear asshown. The target state-of-health is shown as 95% with the dotted linein FIG. 4. The actual modifications of the state-of-health that occursfor batteries A, B, C, shown with the solid lines will not actuallyachieve the target state-of-health during each power exchange event.Rather, with each power exchange event, the modification of the powersupply based on the target state-of-health and the actualstate-of-health of each battery will, over the batteries' life times,result in similar lifespans for each battery. As the system is dynamic,after a first power exchange event, for example, battery A will have ahigher state-of-health using the control methods herein than it wouldhave without using the control methods, while batteries B, C will have alower state-of-health using the control methods herein. At the nextpower exchange event, the state-of-health of batteries A, B, C will becloser in value than they would have been if the control methods hereinwere not used. As subsequent power exchange events occur, the controlmethods herein move the state-of-health values of each of the batteriesA, B, C closer together. Over the life time of the batteries, thestate-of-health of the batteries equalizes.

FIG. 5 illustrates the effect that a power demand that is modified basedon the target state-of-health has on each battery's temperature. Asshown, the broken line represents the internal temperature of batteriesA, B, C if the batteries A, B, C exchanged power at the same powerdemand. The solid lines represent the change in internal temperaturethat occurs due to the change in power exchanged. Because the powerdemand for battery A is reduced to improve its state-of-health, theinternal battery temperature of battery A during power exchange islowered. Because the power demand for batteries B, C is increased toreduce its state-of-health, the internal battery temperature ofbatteries B, C during power exchange is increased.

The methods herein can be implemented in whole or in part by one or moreprocessors which can include computers, servers, or any other computingdevice or system capable of manipulating or processing informationnow-existing or hereafter developed including optical processors,quantum processors and/or molecular processors. Suitable processors alsoinclude, for example, general purpose processors, special purposeprocessors, IP cores, ASICS, programmable logic arrays, programmablelogic controllers, microcode, firmware, microcontrollers,microprocessors, digital signal processors, memory, or any combinationof the foregoing. The methods can be implemented using a general purposecomputer/processor with a computer program that, when executed, carriesout any of the respective methods, algorithms and/or instructionsdescribed herein. In addition or alternatively, for example, a specialpurpose computer/processor can be utilized which can contain specializedhardware for carrying out any of the methods, algorithms and/orinstructions described herein. In the claims, the term “processor”should be understood as including any the foregoing, either singly or incombination. Herein, the terms “program” and “process” should beunderstood to run on the processor.

Further, all or a portion of embodiments described herein can take theform of a computer program product accessible from, for example, acomputer-usable or computer-readable medium. A computer-usable orcomputer-readable medium can be any device that can, for examplecontain, store, communicate, and/or transport the program for use by orin connection with any computing system or device. The medium can be,for example, an electronic, magnetic, optical, electromagnetic, or asemiconductor device. Other suitable mediums are also available.

The methods disclosed may incorporate user input for one or morevariables. The processor used for these methods can include a userinterface, a display, a key pad, a touch screen and any other devicesthat are known to those skilled in the art to assist in the interfacebetween processor and user.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law.

What is claimed is:
 1. A battery deterioration control systemcomprising: a power exchange controller operable to adjust a powerexchange for each of a plurality of batteries to modify astate-of-health of each of the plurality of batteries over time based ona target state-of-health.
 2. The battery deterioration control system ofclaim 1, wherein the power exchange controller is operable to adjust thepower exchange rate by: receiving a total power demand from an upperauthority and each of the plurality of batteries connected to a chargingstation; and adjusting the power exchange between the upper authorityand each of the plurality of batteries by: detecting a batterystate-of-health of each of the plurality of batteries; determining thetarget state-of-health for the plurality of batteries based on thestate-of-health of each of the plurality of batteries; and determining apower exchange with each of the plurality of batteries based on thetotal power demand and a difference between the target state-of-healthand the state-of-health of each battery.
 3. The battery deteriorationcontrol system of claim 2, wherein the power exchange controller isoperable to maintain the power exchange with all of the plurality ofbatteries equal to the total power demand.
 4. The battery deteriorationcontrol system of claim 3, wherein the power exchange controller isoperable to maintain the total power demand to all of the plurality ofbatteries by adjusting an amplitude of power of the power exchange to atleast a portion of the plurality of batteries.
 5. The batterydeterioration control system of claim 2, wherein, when determining thepower exchange, the power exchange controller is further operable todecrease the power exchange with each of the plurality of batterieshaving a state-of-health below the target state-of-health and increasethe power exchange with each of the plurality of batteries having astate-of-health greater than the target state-of-health.
 6. The batterydeterioration control system of claim 2, wherein the targetstate-of-health is determined by averaging the state-of-health of theplurality of batteries connected to the one or more charging stations.7. The battery deterioration control system of claim 2, wherein eachbattery has a connection period and the power exchange controller isoperable to dynamically repeat receiving and adjusting steps throughoutat least a portion of the connection period.
 8. The batterydeterioration control system of claim 1, wherein each vehicle having oneof the plurality of batteries includes an on-board charging system thatreceives commands from the power exchange controller.
 9. The batterydeterioration control system of claim 8, wherein the on-board chargingsystem of each vehicle receives the commands from the power exchangecontroller via at least one of a wired communications link or a wirelesscommunications link.
 10. The battery deterioration control system ofclaim 1, wherein each vehicle having one of the plurality of batteriesis connected to a respective off-board vehicle charging system thatreceives commands from the power exchange controller.
 11. The batterydeterioration control system of claim 10, wherein the respectiveoff-board vehicle charging system for each vehicle receives the commandsfrom the power exchange controller via at least one of a wiredcommunications link or a wireless communications link.
 12. A method forcontrolling battery deterioration comprising: receiving a total powerdemand from an upper authority and each of the plurality of batteriesconnected to a charging station; and adjusting the power exchangebetween the upper authority and each of the plurality of batteries by:detecting a battery state-of-health of each of the plurality ofbatteries; determining the target state-of-health for the plurality ofbatteries based on the state-of-health of each of the plurality ofbatteries; and determining a power exchange with each of the pluralityof batteries based on the total power demand and a difference betweenthe target state-of-health and the state-of-health of each battery. 13.The method of claim 12, wherein determining the power exchange with eachof the plurality of batteries comprises maintaining a total powerexchange with all of the plurality of batteries equal to the total powerdemand.
 14. The method of claim 13, wherein maintaining the total powerexchange with all of the plurality of batteries comprises adjusting anamplitude of power of the power exchange to at least a portion of theplurality of batteries.
 15. The method of claim 12, wherein determiningthe power exchange with each of the plurality of batteries comprisesdecreasing the power exchange with each of the plurality of batterieshaving a state-of-health lower than the target state-of-health andincreasing the power exchange with each of the plurality of batterieshaving a state-of-health greater than the target state-of-health. 16.The method of claim 12, wherein the target state-of-health is determinedby averaging the state-of-health of the plurality of batteries connectedto the one or more charging stations.
 17. The method of claim 12,wherein each battery has a connection period and the method isdynamically repeated throughout at least a portion of the connectionperiod.